1. Field of the Invention
This invention relates to a color camera that is used in the field of TV-studio camera systems, consumer VTR-camera systems, surveillance camera systems and object-detective camera systems.
2. Description of the Prior Art
Within recent several years a demand for consumer-used VTRs has become vast. In accordance with this movement, developments of color cameras has become active and a final goal of this development is to realize a color camera system which is very small sized, easy to use and low in power consumption.
The conventional method to realize signal process parts of the color camera is mainly based on analog signal processing, so that the color camera using this conventional technique has the following disadvantages:
(A) Analog signals which are converted signals of optical-image signal are processed by passing several analog signal process circuits, so an absolute signal to noise ratio (S/N) of the processed analog signals decays as the signal propagate from one process circuit to the next process circuit. For the correction of the S/N decay, very complicated analog circuits and many adjustments thereof are needed. This complication increases the unstability and power consumption rate of the color camera system.
(B) The conventional color camera using color tube and analog circuits has several ten adjustment-points on the production line. This makes it difficult to manufacture the color camera system at a low cost.
(C) The conventional color camera using analog circuits includes so many extra circuit-components to realize an auto-white balanced color correction and auto gamma correction of luminance and chrominance signals.
(D) The conventional color camera using analog circuits require one horizontal delay line as a basic function of the circuits. This delay line is composed of inductance-coils, capacitors, registors and some transistors. This means that it is impossible to fabricate the delay line and the other analog ICs into a monolithic IC chip.
As a summary of the above reasons the conventional design methods using analog signal processing have their own limit in ability of realizing a color camera with very small sized IC circuits, very low power consumption, easy way of use and very simple way of production.